In recent years, solar photovoltaic power generation systems that generate power by means of solar energy have rapidly spread. Such solar photovoltaic power generation systems include a system referred to as the roof installation type in which solar cell modules are installed on the top of a building, and a system referred to as the wall surface installation type in which solar cell modules are installed on a wall surface or a window of a building. Further, there is a system referred to as a ground installation type in which solar cell modules are installed on the ground outdoors.
In these types of solar photovoltaic power generation systems, there may be a problem caused by reflected light from the solar cell module depending on a position or angle at which the solar cell module is installed. For example, there is a problem that when a solar cell module is installed on the roof of a general house, reflected light passes through the window of the neighboring house. That is, there is a problem that sunlight is regularly reflected at the glass surface of a solar photovoltaic power generation module, so that unintended intense light passes into the neighboring house to give an unpleasant feeling to neighborhood residents.
Thus, the development of a solar cell module having a high anti-glare property is desired. That is, the development of a solar cell module with reduced regular reflection from a glass surface when sunlight shines thereon is desired.
A solar cell module having an anti-glare property is disclosed in Patent Document 1. The solar cell module disclosed in Patent Document 1 has an antireflection film provided on the surface of a glass substrate.
Here, the antireflection film is a film which has an optical refractive index between the refractive index of air and the refractive index of glass, and in the solar cell module disclosed in Patent Document 1, reflection of light is suppressed by reducing a difference in refractive index at each interface (air/antireflection film and antireflection film/glass) at which light is incident.
Patent Document 2 discloses a technology in which the surface of an antireflection film is roughened for the purpose of irregularly reflecting sunlight at the surface of a solar cell module.
According to the technology disclosed in Patent Document 2, an anti-glare property is enhanced due to the change in refractive index of the antireflection film, and in addition, light can be irregularly reflected due to the physically irregular structure on the surface, so that higher anti-glare performance is exhibited.
However, for employing the technology disclosed in Patent Document 2, it is necessary to form a considerably thick antireflection film, leading to the problem that the light absorption of the anti-glare film itself increases to deteriorate power generation efficiency.
An invention for solving these problems is disclosed in Patent Document 3.
In the invention disclosed in Patent Document 3, the surface of a glass substrate is subjected to blast processing to roughen the surface, and further, an antireflection film is provided thereon.